Mr Fullagar said the water had reached a depth of 8 metres in the Diamantina River, and the town's airstrip had been especially busy bringing in tourists.

"We've had a huge increase in aviation traffic in and out of Birdsville of people just coming to see what they haven't seen in their lifetimes before — that amount of water coming down through the Channel Country," he said.

"It's nature at its absolute finest."

The South Australian Department of Planning, Transport and Infrastructure said outback roads closed because of flooding included the Birdsville Track from Mungeranie to the Queensland border, the Birdsville Inside Track from Pandie Pandie Station to the Queensland border, and Cordillo Downs Road from the Arrabury turn-off to the Queensland border.